Second cancers after radiotherapy and chemotherapy for early stages of Hodgkin's disease.

In a population of 334 patients treated for Hodgkin's disease by the European Organization for Research and Treatment of Cancer between 1964 and 1971, 21 patients with second primary cancers (SC) were observed: 4 patients with acute leukemias, 3 with non-Hodgkin's lymphomas, and 14 with solid tumors. Time to SC ranged from 2 to 16 years after initial treatment. The relative risk (RR) of acute leukemia for the patients with Hodgkin's disease as compared to the general population was 40 (P less than .001). The RR of leukemia in patients treated by polychemotherapy--mechlorethamine, vincristine, procarbazine, and prednisone--for relapse was 300 (P less than .001). However, the RR of leukemia for those patients who did not experience a relapse was 14 (not significant). The RR of other SC in the overall group was 3.76 (P less than .001). For patients whose relapses were treated by polychemotherapy the RR of SC, leukemia excepted, was 26 (P less than .001), whereas for patients not treated by polychemotherapy for relapse the RR was slightly increased (RR = 3.67; P = .027). The cumulative proportions of acute leukemia at 10 years were 0.7% in the "no-relapse" group and 2.7% in the polychemotherapy group. The cumulative proportions of other SC at 10 years was 1.3% in the no-relapse group, 7.2% in the group of patients not treated by polychemotherapy after relapse, and 8.4% in the polychemotherapy group. The first important risk factor for developing an SC was polychemotherapy, and the second was age over 40 years. These data suggest that combination chemotherapy may be responsible for both acute leukemias and other SC.